Variable angle adaptive plate

ABSTRACT

A device for supporting and/or assisting in bone fusion, particularly in the spine, is described. A plate member is provided, along with two or more attachment members that are anchorable to bones. In one embodiment, the plate member has a slot near one end and an aperture at another end. The attachment members include threaded posts for connection to the plate member via the latter&#39;s slot(s) and aperture(s). Alternatively, attachment members need not have a threaded post, and attachment members may be connected to the plate member via a bone bolt or similar fixation member. The slot(s) allow a single plate member to be used for a variety of operative situations and anatomies. A device for repositioning bones and a method for using the disclosed devices is also described.

FIELD OF THE INVENTION

The present invention is generally in the field of orthopedic implantsand corrective devices, and specifically concerns plate systems forcorrecting spinal injuries or abnormalities.

BACKGROUND OF THE INVENTION

Many implant systems are known for correcting orthopedic abnormalities,whether such abnormalities are naturally occurring or are due to diseaseor injury. For example, in cases of abnormal spinal curvature, such asscoliosis, or in cases in which one or more vertebrae must be repairedor removed, such as in tumor or fracture cases, it is common to implanta device that provides stability and support to the spine.

Two particular types of systems are well known for such repair ortherapy. First, rod-based systems are known, in which a rod or bar isfixed to the spine via bone screws or hooks. Generally, the screws orhooks are implanted into one or more spinal segments, the spine isadjusted, and the rod or bar is fixed to the screws or rods to hold thespine in the corrected position. These types of systems are commonlyused to correct an abnormal curvature and/or to support weak or injuredvertebrae in an approximately normal curvature. One example of such asystem is disclosed in U.S. Pat. No. 5,005,652 to Cotrel.

A second type of system for spinal therapy is a plate-based system. Ingeneral, a flat plate with one or more slots or holes through it isattached to one or more spinal segments by bone screws or bolts. Suchplates are commonly used for the purpose of immobilizing the spinalsegment(s) and promoting healing of vertebrae suffering from injury,tumor removal or other trauma or abnormality. Commonly, fusion among thevertebrae in the segment(s) is a desired therapeutic outcome, andplate-based systems are generally suited to promotion of fusion. As anexample of such a plate-based system, see U.S. Pat. No. 6,315,779 toMorrison, et al., the entirety of which is incorporated herein byreference.

In some cases, plate-based systems directly attached to a bone may beincorrectly used or placed. For example, a slotted plate member that isfixed to a bone directly via a screw or bolt may fail through wideningof the slot if the screw or bolt is over-tightened, or if it is placedon bone(s) in a way that could over-stress the plate. As forces fromover-tightening or misplacement are transmitted to the plate, andspecifically to the sides of the longitudinal slot through the plate,such forces can cause the sides of the plate to bow outward throughrepeated stress. The result is that the slot widens, which may allow theattaching bolt or screw head to move with respect to the slot, reducingor eliminating the immobilizing capability of the plate system.

To overcome the possibility for such failure, several different optionshave been proposed. In U.S. Pat. No. 5,613,967 to Engelhardt, a holdingbracket is placed over the plate. As the sides of the plate experienceoutwardly directed forces, the bracket holds the sides of the plate sothat they do not bow. In U.S. Pat. No. 6,315,779 to Morrison et al, astabilizing member is inserted within the plate. The stabilizing membercontacts the bolt or screw that is inserted into a vertebra, rather thanthe plate contacting the bolt or screw, and the stabilizing membercannot be bowed outward.

Some prior art plate-based systems also suffer from a risk of looseningdue to backing out of a screw inserted into a vertebra. If a bone screwbacks out, e.g. due to improper insertion or unanticipated stress, aplate member is not securely held in contact with the vertebra(e) so asto provide immobilizing support. Fusion, if not already completed, canbe interrupted or counteracted, and injury to the vertebrae orassociated tissue is possible. Use of caps or other parts over the headsof bone screws is known to help maintain the screws in their insertedpositions and sustain secure contact between vertebrae and a plate.However, such devices add to the number of parts, particularly smallparts, that a surgeon must handle in implanting the system.

Accordingly, there remains a need for an improved plate-based systemthat will address these shortcomings.

SUMMARY OF THE INVENTION

In general, an embodiment of the invention can include a plate memberhaving a first end with a slot and a second end with an aperture thatmay be round, elongated, or have another shape. A plurality ofattachment members are connected to the plate member, each of theattachment members having at least one hole for receiving a portion of abone anchoring member and each adapted for contact with a vertebra.Posts are connected to two of the attachment members and extend throughthe plate member's slot and aperture in said plate member respectively.Nuts or other locking caps or devices are provided for the posts forlocking together the attachment members and the plate member.

In another embodiment, a plate member is provided having a first endwith a slot and a second end with an aperture. An attachment memberhaving at least one hole for receiving a portion of a bone anchoringmember and adapted for contact with a vertebra connects to the platemember. A bolt having a lower portion threaded for insertion into a boneand an upper threaded portion is also provided, and the upper portion ofthe bolt is adapted to be inserted through a hole in the attachmentmember and the slot in the plate member. A nut threads onto the upperthreaded portion of the bolt for locking together the attachment memberand plate member.

In another embodiment, a plate member having a first end with a slot, asecond end with an aperture, and a second slot, a portion of which isbetween the first slot and the aperture, is provided. First and secondattachment members each having at least one hole therethrough areconnected to the plate member proximate to the first slot and theaperture, respectively. First and second screws for attaching theattachment members to a bone via the holes in the attachment members arealso provided. The plate member includes at least a portion that coversat least a portion of the first and second screws.

In a further embodiment, a method is provided including attaching afirst attachment member having a post and a roughened upper side to afirst vertebra, and a second attachment member having a post and aroughened upper side to a second vertebra. A plate member having a slotand an aperture is connected to said attachment members, such that thefirst attachment member's post extends through the slot and the secondattachment member's post extends through the aperture. A repositioningdevice is connected to the posts of the attachment members, and therepositioning device is operated to perform at least one of: distractionof the attachment members, compression of the attachment members, androtation of at least one of the attachment members. The repositioningdevice may include first and second rods adapted to connect to theattachment members' posts, a first clamp connected to the first rod anda second clamp connected to the second rod, a bar connected to theclamps and having teeth along at least one edge, and a pinion mechanismhaving teeth that engage said teeth of said bar connected to the firstclamp, so that turning the pinion mechanism causes the first clamp andthe first rod to move with respect to the second clamp and the secondrod. In certain embodiments of the method, the rods are threaded ontothe attachment members' posts. Operation of the repositioning device canbe continued until the vertebrae are in a desired relative position, andthe plate member can be locked with respect to the attachment members sothat the vertebrae are maintained substantially in the desired relativeposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of one embodiment of a plate system incorporatingthe present invention.

FIG. 2 is a side view of the embodiment shown in FIG. 1.

FIG. 3 a is a top view of an embodiment of an attachment member usefulin the plate system shown in FIG. 1.

FIG. 3 b is a cross-sectional view of the embodiment shown in FIG. 3 aalong the lines 3 b-3 b in FIG. 3 a, viewed in the direction of thearrows.

FIG. 3 c is a side view of the embodiment shown in FIG. 3 a.

FIG. 3 d is a bottom view of the embodiment shown in FIG. 3 a.

FIG. 4 is a bottom view of an embodiment of a plate member useful in theplate system shown in FIG. 1.

FIG. 5 is a partial cross-sectional view of a screw useful in the platesystem shown in FIG. 1.

FIG. 5A is a cross-sectional view of the embodiment of the screw shownin FIG. 5 along the lines 5 a-5 a in FIG. 5, viewed in the direction ofthe arrows.

FIG. 6 is a top view of another embodiment of a plate systemincorporating the present invention.

FIG. 7 is a side view of the embodiment shown in FIG. 6.

FIG. 8 is a top view of another embodiment of a plate systemincorporating the present invention.

FIG. 9 is a side view of the embodiment shown in FIG. 8.

FIG. 10 is a end view of the embodiment shown in FIG. 8.

FIG. 11 is a side view of an embodiment of an attachment member usefulin the plate system shown in FIG. 8.

FIG. 12 is a side view of an embodiment of a repositioning apparatusaccording to the present invention.

FIG. 13 is a top view of the embodiment shown in FIG. 12.

FIG. 14 is an end view of the embodiment shown in FIG. 12.

FIG. 15 is a bottom view of the embodiment shown in FIG. 12.

FIG. 16 is a side view of the embodiment of a rod shown with theembodiment of a repositioning apparatus in FIG. 12.

FIG. 17 is a cross-sectional view, taken along the lines 17-17 andviewed in the direction of the arrows, of the embodiment shown in FIG.16.

FIG. 18 is a cross-sectional view, taken along the lines 18-18 andviewed in the direction of the arrows, of the embodiment shown in FIG.16.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiment illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein, beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring now to FIG. 1, there is shown a first embodiment of a platesystem according to the present invention. In that embodiment, a platemember 20 is connected to attachment members 22. Attachment members 22are intended to be attached to individual vertebrae, as will bediscussed further hereafter. Plate member 20 is to be connected toattachment members 22, so that such individual vertebrae are immobilizedwith respect to each other.

As shown in FIGS. 1, 2 and 4, plate member 20 is a relatively flat,elongated member having a longitudinal axis L. As it is designed forimplantation in a living body, it is preferably made of a materialcompatible with such a use, e.g. titanium, stainless steel, ceramicsand/or hard plastics. At a first end 24, plate member 20 includes anelongated slot 26. In a specific embodiment, slot 26 may have a lengthof from four to ten millimeters. Of course, the length of slot 26 can beincreased or decreased depending on the overall size of plate member 20and/or the size of the post that extends through slot 26 (discussedbelow). Further, it will be recognized that the length and/or breadth ofslot 26, as well as the overall dimensions of plate 20 and others of itsfeatures, can be made larger or smaller depending upon the place in thebody into which plate member 20 is to be implanted. For example, smallerdimensions may be preferred or required if plate member 20 is to be usedin the cervical section of the spine, whereas somewhat larger dimensionsmay be preferred if plate member 20 is to be used in the thoracicregion, or still larger dimensions if used in the lumbar or sacralregion of the spine.

End 24 of plate member 20 includes an underside portion 28 thatpreferably includes a roughened surface, e.g. knurled, grooved, orotherwise, to improve the connection between end 24 of plate member 20and a corresponding attachment member 22. Knurling of surface 28 ispreferred due to relative ease of manufacture while allowing attachmentmember 22 to connect to end 24 of plate member 20 in a wide range ofpositions. Plate member 20 has a second end 30 that is opposed to end24, and has an aperture 32 that extends through plate member 20. In theillustrated embodiment, aperture 32 is a circular hole. It will beunderstood that aperture 32 can have other shapes, such as a square orother polygonal hole or an elongated slot. End 30 further includes aroughened underside portion 31, which has one or more of the types ofroughening described above with respect to underside portion 28 of end24. In the embodiment shown in FIG. 4, end 30 includes a number ofradial splines extending from aperture 32 on underside 31 of platemember 20. Other types of roughening, such as the knurling shown withrespect to end 24, could be used instead or in addition to such splineson underside portion 31.

Ends 24 and 30 are generally somewhat wider than middle portion 36 inthis embodiment of plate member 20. The wideness of ends 24 and 30provide additional area to plate member 20 in regions in which platemember 20 is connected to attachment members 22, thus enabling a firmeror stronger connection between plate member 20 and attachment members22. The narrower middle portion 36 uses less material and enablesplacement of plate member 20 closer to spinal structures such as spinalprocesses or pedicles than might otherwise be the case.

Turning now to FIGS. 1, 2 and 3 a-3 d, there is shown an embodiment ofattachment member 22. In that embodiment, attachment member 22 has agenerally rectangular base 33 and includes two holes 34 placed indiagonal corners of base 33. However, it will be understood that holes34 may occupy different locations in attachment member 22. For example,in other embodiments holes 34 may be in the corners along the same side,or amid opposing sides, of attachment member 22. In embodiments in whichattachment member 22 has a narrow rectangular base 33 (e.g. where thewidth of base 33 is not much greater than an appropriate diameter forholes 34), holes 32 may be positioned at or near the ends of base 33 ofattachment member 22. In a particular embodiment, holes 34 may includeupper surfaces (not shown) that enable countersinking of bone screws.Although two holes 34 are shown in the illustrated embodiments ofattachment members 22, it is possible to construct an attachment member22 (or 22′ or 22″ as described below) with only one or with more thantwo holes 34. Post 36 may include a tool-engaging surface, such asinternal hexagonal print 37, to assist in moving or turning attachmentmember 22.

The illustrated embodiment of attachment member 22 includes a post 36,which is externally threaded in one specific embodiment. Post 36 may bemade integral with the base portion of attachment member 22.Alternatively, post 36 may be fashioned separately and attached to base33 of attachment member 22 by welding, threaded engagement, or otherknown connection techniques. For such alternative cases, an aperture(e.g. a threaded aperture) or other mating area in base portion 33 ofattachment member 22 may be provided for post 36. It is preferred thatpost 36 is attached to the base portion of attachment member 22 prior touse by a surgeon, e.g. during manufacture of attachment member 22, so asto minimize the effort of the surgeon. Post 36 is shown in approximatelythe center of base portion 33 of attachment member 22, but may be placedin other positions.

Attachment member 22 may also include one or more fixation prongs 38having a relatively sharp or pointed fixation end 40. Prongs 38 may bemade integral with base 33 of attachment member 22, or may be attachedto base 33 as described above with respect to post 36. In theillustrated embodiment, prongs 38 are located in diagonal corners ofbase portion 33 of attachment member 22, e.g., in the corners havingholes 34.

As with the bottom surfaces 28 and 31 of plate member 20, in a preferredembodiment a top surface 39 of attachment members 22 is knurled orotherwise roughened. In a specific embodiment, an attachment member 22designed to connect with end 24 of plate member 20 is knurled on topsurface 39 in a similar fashion to the knurling on surface 28 of platemember 20. This will allow such an attachment member 22 to connect toplate member 20 anywhere in the region of slot 26 of plate member 20,and in any orientation. An attachment member 22 designed to connect toend 30 of plate member 20 may include radial splines on top surface 39extending from post 36 compatible with undersurface 31 of plate member20. Such splines would allow a secure connection while allowing such anattachment member 22 to rotate with respect to plate member 20. Radialsplines are appropriate where an attachment member 22 is to be used withan aperture that does not allow translation of attachment member 22 withrespect to plate member 20 (e.g. circular aperture 32). If translationcapability between an attachment member 22 and plate member 20 isdesired, as with an attachment member 22 proximate to slot 26 of platemember 20, splines may inhibit secure connection in differenttranslational positions of attachment member 22 relative to plate member20.

There is shown in FIG. 5 a standard bone screw 50 that may be used withattachment member 22. Screw 50 has a head portion 52 and a threadedshaft portion 54, as is known in the art. Head 52 includes an aperture56 adapted to accept one or more tools useable to insert a screw into abone. In the illustrated embodiment, aperture 56 includes an internalhexagonal print. Screw 50 may be cannulated, that is, it may have acannula 58 extending from aperture 56 through the shaft 54 of screw 50.Screw 50 may be a fenestrated screw, i.e. it includes several holes 59in shaft 54. In an embodiment in which screw 50 is both cannulated andfenestrated, holes 59 can be made to extend from the surface of shaft 54to the cannula 58. In one particular embodiment, holes 59 are placed 120degrees apart around the circumference of shaft 54. Holes 59 intersectthe surface of shaft 54 at a root of the thread around shaft 54 in theembodiment shown in FIG. 5, but it will be understood that holes 59could intersect that surface at a thread crest or between a root and acrest. Cannula 58 and/or holes 59 can serve several purposes, includingadministration of bone growth-inducing substance (e.g. bone morphogenicprotein, or BMP), medicinal preparations (e.g. coagulants orantibiotics), or other fluids or substances to be used or placed at thesite of implantation. Such substances may be inserted through cannula 58to holes 59, if both are provided. Cannula 58 and/or holes 59 may alsoallow bone tissue to grow into screw 50.

A nut 60 is also provided for mating with post 36 of attachment member22 and locking together attachment member 22 and plate member 20. In theillustrated embodiment, nut 60 is shown as a standard hexagonalinternally-threaded nut compatible with an embodiment of post 36 havingexternal threads. In another embodiment, nut 60 could be replaced by anut and washer combination such as that shown in U.S. Pat. No. 6,315,779to Barker et al., which is incorporated herein by reference. Use of thatspecific combination would allow multi-axial positioning of attachmentmember 22 with respect to plate member 20. In yet another embodiment,nut 60 could be a lock nut having a lockable slot, such as that shown inU.S. Pat. No. 5,915,902, which is incorporated herein by reference.

As seen in FIG. 1, when assembled a portion of plate member 20 covers aportion of head 52 of one or more screws 50 that connect attachmentmembers 22 to bone. It will be appreciated that the entire head of oneor more screws 50 could be covered by plate member 20. Plate member 20may contact heads 52 of screws 50 when nuts 60 are tightened to lockplate member 20 and attachment members 22 together, particularly inembodiments in which holes 34 of attachment members 22 do not allow forcountersinking of heads 52.

To use plate member 20, a surgeon makes one or more incisions into apatient, and obtains access to two or more vertebrae defining one ormore spinal segments that are to be implanted for stabilization, fusion,or other purposes. Once access is established, the surgeon may preparethe vertebrae by removing bone or adjacent tissue, as is known in theart. Attachment members 22 may then be placed in contact with theirrespective vertebrae. If one or both attachment members 22 are providedwith prongs 38, then such prongs 38 can be partially or completelyanchored into the vertebral tissue so as to hold attachment members 22in place while further procedures are performed. Holes are prepared inthe vertebrae corresponding to holes 34 of each attachment member 22.This may be done via a drill or auger placed through holes 34 ofattachment member 22, or by other procedures known in the art. The holesin the vertebrae may be tapped. It will be appreciated that these stepsmay be performed in various orders, e.g. holes in the vertebrae can bedrilled prior to introduction of one or more attachment members 22 ifthe site(s) for placement of attachment member(s) 22 are sufficientlyprecisely identified. Fixation elements (e.g. screws 50) are then placedthrough holes 34 of each attachment member 22, and threaded into theholes in the associated vertebrae. Screws 50 are threaded into thevertebral tissue until head portion 52 is securely in contact withattachment member 22 and attachment member 22 is securely fixed betweenhead 52 and the associated vertebra.

Plate member 20 is then placed over attachment members 22. Slot 26 ofplate member 20 is placed over post 36 of one attachment member 22.Similarly, hole 32 of plate member 20 is placed over post 36 of thesecond attachment member 22, so that such threaded post 36 extendsthrough hole 32. Nuts 60 may be threaded or otherwise placed onto one orboth posts 36 so that plate member 20 is kept proximate to attachmentmembers 22, but not so tightly that adjustments to the vertebrae and/orto the relative positions of plate member 20 and attachment members 22cannot be made. The relative distance or position of the vertebrae canbe changed so that they form part of a normal spinal curvature and canbe fused, or otherwise to treat effectively the existing malformation,injury, or other condition of the given vertebral segment or nearbyvertebra(e). During this repositioning, plate member 20 can move withrespect to attachment members 22. Specifically, plate member 20 canrotate around the post 36 that extends through hole 32 in plate member20. Plate member 20 can also translate and rotate with respect to post36 that extends through slot 26 in plate member 20. Of course,manipulation of the vertebrae can also take place prior to positioningattachment members 22 and/or plate member 20. Consequently, the surgeoncan perform distraction, compression, and/or rotation on one or morevertebral segments prior to or while plate member 20 is looselyconnected to attachment members 22.

When the vertebral segment is positioned as desired, and attachmentmembers 22 and plate member 20 are connected to the vertebrae asdescribed above, nuts 60 are tightened on posts 36 so as to presstogether plate member 20 and attachment members 22 and hold them inplace relative to each other. In embodiments in which attachment members22 include knurling or other roughening on an upper side 39, and platemember 20 includes similar knurling or roughening on its undersideportions 28 and/or 31, the pressing together of plate member 20 andattachment members 22 will cause these roughened surfacesto-interdigitate or otherwise engage, and provide substantially greatersecurity of connection at the interface between plate member 20 andattachment members 22.

Referring now to FIGS. 6 and 7, there is shown another embodiment ofplate member 20′. Plate member 20′ is very similar to plate member 20,and includes a first end 24′ having a slot 26′, and a second end 30′having a substantially round aperture (not shown) that corresponds tohole 32 of plate member 20. Plate member 20′ also preferably includesroughened underside portions corresponding to underside portions 28 and31 of plate member 20. In the illustrated embodiment, end 24′ includes asection 70 that extends laterally with respect to slot 26′. Similarly,end 30′ includes a laterally-extending section 72. It will be seen thatplate member 20′ is in essence a substantially rectangular plate with aslot 26′ and a hole (not shown) off the longitudinal center of platemember 20′, and with a substantial amount of material removed from atleast middle section 36′ of plate member 20′, so as to conservematerial. An alternative embodiment, therefore, could be a rectangularplate member 20′ with a slot and a hole off the longitudinal center ofthe plate member.

Attachment members 22′ are substantially the same as attachment members22, with the exception that attachment members 22′ do not include anattached or integral post 36, as attachment members 20 do. In otherrespects, attachment members 22′ are essentially the same as attachmentmembers 20. Thus, attachment members 22′ include two holes correspondingto holes 34, and a roughened upper surface that corresponds to surface39 of attachment members 20. Other features that correspond to featuresdescribed above are denoted in FIGS. 6 and 7 with a prime (e.g. nut 60′corresponds to previously described nut 60).

In this embodiment, a single screw 50 is used with a given attachmentmember 22′. Note that sections 70 and 72 of plate member 20′ constituteportions of plate member 20′ that cover all or a portion of screws 50anchoring attachment members 22′ to bone. In place of a second screw 50for a given attachment member 22′, a bone bolt 76 is provided.Embodiments of bone bolt 76 are described in U.S. Pat. No. 6,315,779 toBarker et al., the entire disclosure of which is incorporated herein byreference. Bolt 76 generally includes a threaded portion 78, a medialhead portion (not shown), and a machine threaded upper portion 80. Themedial head portion would be larger in diameter than holes 34′ ofattachment member 22′, to anchor members 22′ to a bone. The medial headportion can be smaller than the width of slot 26′ of plate member 20′.

In use, plate member 20′ and attachment members 22′ are placed in amanner very similar to that described above with respect to plate member20 and attachment members 22. Attachment members 22′ are placed incontact with respective vertebra, and are affixed to the respectivevertebra via a screw 50 through hole 34′ in attachment members 22′ andinto the bone. Bolts 76 are then inserted into holes 34 throughattachment members 22′ and into the bone. Plate member 20′ is placedover the machine threaded portion 80 of bolts 76 and, after anynecessary repositioning of the vertebra, nuts 60 are tightened down onmachine threaded portions 80 of bolts 76 to lock plate member 20′ withattachment members 22′ and their respective vertebrae.

A further embodiment is shown in FIGS. 8-11. Features in this embodimentcorresponding to features described in connection with previousembodiments are denoted in FIGS. 8-11 by a double prime (e.g. nut 60″corresponds to previously described nut 60). Plate member 20″ issubstantially rectangular and has a first slot 26″ at a first end 24″, asecond end 30″ with a substantially cylindrical aperture (not shown, butcorresponds to aperture 32 in plate member 20 described above), and amiddle slot 100. As shown in FIG. 10, plate member 20″ has an undersidewith a concave curvature. Like plate member 20, plate member 20″preferably includes roughening on underside portions 28″ and 31″ inproximity to slot 26″ and the aperture near second end 30″.

Attachment member 22″ is shown in greater detail in FIG. 11. Attachmentmember 22″ is essentially the same as attachment member 22, with theexception that it has an underside 104 that has a concave curvature, andan upper side 106 that has a convex curvature substantially the same asthe concave curvature of underside 28″ of plate member 20″.

As seen in FIG. 10, when assembled a portion of plate member 20″ coversa portion of head 52 of one or more screws 50, as further describedabove with respect to plate member 20.

Plate member 20″ can be used to fix or interconnect two or more adjacentvertebrae. If only two vertebrae are to be instrumented, plate member20″ and attachment members 22″ are used essentially as described above.Where three or more vertebra are to be instrumented, attachment members22″ are attached to the outermost (i.e. most superior and most inferior)vertebrae essentially as described above. Additionally, attachmentmembers 22, 22′, and/or 22″ may be attached to one or more of thevertebrae between such outermost vertebrae, and connected to platemember 20″ through slot 100, in substantially the manner describedabove. Bolts (e.g. bolt 76) can be inserted without an attachment memberinto a vertebra and extend through slot 100 to provide additionalstability or correction. It will be observed that other types of implantparts compatible with a slotted plate may also be used with respect toplate member 20″ and central slot 100.

Referring now to FIGS. 12-15, there is shown an embodiment of a bonerepositioning apparatus 200 for distraction, rotation, holding in place,and/or other manipulation of bones via attachment members 22. Apparatus200 includes two elongated rods 202, 204 that are connected to atransverse bar 206. In the specific embodiment shown, rod 202 isconnected to bar 206 via clamp 208, which is closed by thumb screw 210,while rod 204 is connected to bar 206 via clamp 212 and thumb screw 214.A pinion mechanism 216 may be connected to clamp 212 to interact withbar 206, as further described below.

Referring now to FIG. 16-18, an embodiment of rod 202 is shown, and itshould be understood that the following description is equallyapplicable to rod 204. In the illustrated embodiment, rod 202 has agenerally cylindrical outer sleeve 202 a and an inner shaft 202 bextending through at least a portion of outer sleeve 202 a. Outer sleeve202 a may include flattened portions 218 to assist the surgeon ingripping, turning or otherwise maneuvering sleeve 202 a and/or rod 202.Inner shaft 202 b may also be generally cylindrical, and may also haveflattened portions 220 for gripping, turning or other maneuvering. Aconnecting portion 222 may be included on or with sleeve 202 a and/orshaft 202 b for accommodating clamp 208. Connecting portion 222 maysimply be a part of the generally cylindrical shaft or sleeve, as shownin FIG. 15, or it may be a cylindrical, annular or other-shapedprojection integral with or surrounding at least a portion of therespective sleeve or shaft. In the illustrated embodiment, sleeve 202 ais movable translationally and rotationally with respect to shaft 202 b.Alternatively, sleeve 202 a and shaft 202 b may be fixed together orintegral with each other.

As shown in FIG. 16, rod 202 has distal end 232 configured to connect toattachment members 22. In one particular embodiment, distal end 232includes sleeve distal end 232 a and shaft distal end 232 b. Sleevedistal end 232 a may include internal threads 233 for screwing onto theembodiment of post 36 of attachment member 22 that has external threads.Alternatively, or in addition, sleeve distal end 232 a may have an endsurface roughened for mating with or otherwise configured to connect toa roughened top surface 39 of attachment members 22, or sleeve distalend 232 a may have detent mechanism(s), internal prints, or other knownstructure to connect with, hold to and/or turn post 36 of attachmentmember 22. Shaft distal end 232 b may be provided with an external printsuch as hexagonal head that can interact with the head of post 36 ofattachment member 22.

Bar 206 is shown in one embodiment as a flattened substantiallyrectangular solid. It will be understood that bar 206 could have any ofa number of shapes, such as an elongated solid with a cross-section inthe shape of a circle, square, triangle or other polygon. Theillustrated embodiment of bar 206 includes a set of teeth 238 along oneside, and a scale of numbers can be included along a top surface 240.

Clamp 208 is attached to or integral with bar 206, and in a particularembodiment is a simple C-clamp-type mechanism, with an aperture 242 toaccommodate rod 202, sleeve 202 a, shaft 202 b, and/or connectingportion 222. Tightening thumb screw 210 narrows aperture 242 and clampsrod 202. Clamp 212 has an essentially identical connection to rod 204.Clamp 208 further includes a transverse extension 244, making clamp 204approximately L-shaped. Extension 244 includes a channel 246 sized toaccommodate bar 206 therein. Extension 244 may also have indicator linesfor use with a numeric scale, if provided on top surface 240 of bar 206,to gauge the extent of distraction or other manipulation of bones. In aspecific embodiment extension 244 also includes a hole 248 communicatingwith channel 246, and pinion mechanism 216 extends through hole 248.Pinion mechanism 216 thus may contact teeth 238 of bar 206 inrack-and-pinion fashion, so that turning pinion mechanism 216 results inlinear movement of clamp 212 with respect to bar 206. A locking pawl 250may be included. In the illustrated embodiment, pawl 250 is aspring-loaded lever attached to clamp 208, having a pushing surface 252and a tooth-engaging end 254. Pushing on pushing surface 254 rotatespawl 250 to disengage tooth-engaging end 254 from teeth 238 of bar 206.Releasing pushing surface 254 allows tooth-engaging end 254 to resumeits spring-biased position engaging teeth 238. Preferably clamps 208,212 and bar 206, and pinion mechanism 216 if included, are pre-assembledprior to surgery to form essentially a single “rack” unit for thesurgeon's use.

When attachment members 22 are attached to bones, e.g. vertebrae, asdescribed above, compression, distraction, rotation or other maneuveringof the bones can be accomplished via bone repositioning apparatus 200.Rods 202, 204 are inserted into the surgical site and connected toattachment members 22. As noted above, parts of rods 202, 204 (e.g.internal threads 233 of sleeve distal end 232a) connect to rod 36 and/orroughened top surface 39 of attachment members 22. The “rack” unit(pre-assembled bar 206, clamps 208, 212, and pinion mechanism 216)portion can be connected to rods 202, 204 by placing clamps 208, 212 sothat a portion of rods 202, 204 respectively extend through apertures242 of clamps 208, 212. Clamps 208, 212 are then tightened via thumbscrews 210, 214. With the parts of the repositioning device 200assembled and.tightened, the surgeon can now apply a distractive orcompressive force through the pinion mechanism 216. Turning pinionmechanism 216 in one direction causes the distance between clamps 208,212 (and rods 202, 204 and their connected bones) to increase, i.e.distraction of vertebrae occurs. Turning pinion mechanism 216 in theother direction, conversely, provides a compression of vertebrae. Ifpresent, a scale on surface 240 of bar 206 and indicator lines on clamp212 enable the surgeon to track the amount of distraction (orcompression), and may correspond to a desirable measure such as the sizeof a graft, intervertebral spacer, plate, or other implant.

In the illustrated embodiment, pawl 250 is oriented to allow distractionwhile pawl 250 is in its spring-biased state (i.e. when tooth-engagingend 254 engages teeth 238), while inhibiting or preventing compression.To enable compression of vertebrae, pawl 250 may be disengaged fromteeth 238, or may be oriented 180 degrees opposite to what is shown inFIG. 12, or may be left out of apparatus 200 altogether.

Rotation of a vertebra or other bone is also possible. After rod 202 isconnected to an attachment member 22, it will be appreciated that rod202 (or sleeve 202 a or shaft 202 b thereof) can be rotated, and suchrotation transmitted to the attachment member 22 to which rod 202 isconnected and the corresponding bone. A wrench, nut-driver or other toolcan be used in connection with flattened portions 218 of outer sleeve202 a and/or flattened portions 220 of inner shaft 202 b to turn rod202. If shaft 202 b is movable with respect to sleeve 202 a, and shaft202 b includes a connection to attachment member 22 such as thehexagonal print described above, then only shaft 202 b need be rotatedin order to rotate attachment member 22 and the corresponding bone. Ofcourse, the same process for using rod 204 to rotate a bone can also beused. Further, if rotation is desired after connection of clamps 208,212 to rods 202, 204, then thumb screws 210, 214 may have to be loosenedin order to allow rotation of part or all of rods 202, 204.

Once the surgeon has introduced the desired distraction, compressionand/or rotation to a vertebral segment or other bone(s), positioningapparatus 200 can be locked via thumb screws 210, 214 and pawl 250 topreserve the relative positions of rods 202, 204 and their correspondingattachment members 22. With the segment thus held in the desiredposition, the surgeon can then prepare the bones for furtherimplantation or other treatment. For example, the surgeon can removetissue from between vertebrae and prepare vertebral surfaces for acage-type vertebral implant such as that shown in U.S. Pat. No.5,782,919 to Zdeblick et al. (the entire disclosure of which is herebyincorporated herein by reference), or similar implant or graft.

The positioning apparatus 200 or parts of it can also be used inassociation with the plate member 20 described above. Vertebrae in oneor more vertebral segments are prepared and implanted with attachmentmembers 22 and plate member 20 is placed atop them, as described above.Nuts 60 are threaded onto rods 36 of attachment member as describedabove, but are not tightened. Positioning apparatus 200 is thenintroduced and connected to attachment members 22. For example, rod 202(including sleeve 202 a and shaft 202 b, each of which are movable withrespect to each other) is connected to an attachment member 22 so thatsleeve distal end 232 a is adjacent to or abuts plate member 20 and nut60 (for example by threading onto post 36), and shaft distal end 232 bconnects with post 36 of attachment member 22 (for example via anexternal print compatible with internal print 37 of post 36). Rod 204may similarly be connected to the second attachment member 22. Theremaining parts of the embodiment of positioning apparatus 200 describedabove are used as previously disclosed.

The surgeon then introduces the desired compression, distraction and/orrotation via positioning apparatus 200. During such procedure(s), one orboth attachment members 22 may change position with respect to platemember 20. When manipulation of attachment members 22 and theircorresponding vertebrae is complete, positioning apparatus 200 is lockedto preserve their relative positions. Nut 60 can then be tightened witha wrench placed below sleeve 202 a. If sleeve 202 a is provided with aninternal print at distal end 232 a corresponding to nut 60, in additionto or instead of threads 233, sleeve 202 a can be rotated to tighten nut60 down onto plate member 20, thereby locking plate member 20 toattachment member 22, and holding the corresponding vertebrae in thedesired relative position.

The preceding discussion has principally concerned the embodiment ofattachment member 22 that includes a rod 36. As noted previously, rods202, 204 can include roughening at a distal end (e.g. distal end 232 aof sleeve 202 a) that mates or otherwise connects with roughened uppersurface 39 of attachment member 22. Thus, even if the embodiment ofattachment member 22 not having a rod is used, positioning apparatus 200can be used.

All parts described herein should be manufactured of titanium, stainlesssteel, certain ceramics or hard plastics, or other material that arebiocompatible and are sufficiently sturdy to support human or animalbone structures, and particularly the spine. It will be further beobserved that although certain screws and bolts have been describedabove, that other types of bolts, screws, or other fixation members maybe used in connection with the present invention.

It will be appreciated that the above embodiments can be constructed foruse in the sacral, lumbar, thoracic and/or cervical regions of thespine, and for use along the junctions of those regions. The size of agiven embodiment will depend on the region in which it is used. It isalso contemplated that embodiments can be used in connection with otherbony structures.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected. For example, nut 60 is provided as thelocking mechanism for use with a threaded post 36. Other types of postsand locking mechanisms could be used, such as a post that includesgrooves, holes or ridges and a lock that has sufficiently strongratchet, pawl, spring or detent-type holding structure. As anotherexample, although plate members 20, 20′ and 20″ are described and shownwith a longitudinal slot at one end and a circular aperture at theother, it is possible for the plate member to have a slot at each end,or for a slot to have a non-zero angle with respect to a longitudinalaxis of the plate member. As still a further example, any embodiment ofa plate member may have roughening on its entire underside, and may havea concave underside. In yet a further example, rods 202, 204 ofrepositioning apparatus 200 may be internally configured to allow nut 60to placed on post 36 after repositioning occurs. For instance, sleeve202 a a may be internally hollow and hexagonal shaped to accommodate nut60, and shaft 202 b may be smaller than the hole through nut 60 and havean external print or other structure to hold post 36. Once shaft 202 bholds post 36, nut 60 can be inserted around shaft 202 b and withinsleeve 202 a, so that nut. 60 slides down and onto post 36. Rotation ofsleeve 202 a then tightens nut 60 onto post 36.

1-35. (canceled)
 36. An apparatus comprising: a plate having a firstend, a second end, a lower side and a perimeter, a slot proximate tosaid first end, and an aperture proximate to said second end; anattachment member having at least one hole therethrough, said attachmentmember adapted to contact a vertebra and to connect to said plateproximate to one of said slot and said aperture; a screw having a shaftand a head portion at one end of said shaft for anchoring saidattachment member to a bone, said screw being in said at least one holethrough said attachment member, wherein at least a portion of saidperimeter of said plate covers at least a portion of said head of saidscrew when said attaching member and said plate are connected, such thatsaid head is between a portion of said attaching member and said lowerside of said plate.
 37. The apparatus of claim 36 further comprising: asecond attachment member adapted to contact a vertebra and to connect tosaid plate proximate to the other of said slot and said aperture; and asecond screw for attaching said second attachment member to a bone withat least a portion of said second screw being in said hole through saidsecond attachment member; and wherein at least a portion of saidperimeter of said plate covers at least a portion of said second screwwhen said second attaching member and said plate are connected.
 38. Theapparatus of claim 37 further comprising: a first post connected to afirst of said attachment members and extending through said slot in saidplate member and a second post connected to a second of said attachmentmembers and extending through said aperture in said plate; and a firstlocking means for mating with said first post and locking together saidattachment member connected to said first post and said plate, and asecond locking means for mating with said second post and lockingtogether said attachment member connected to said first post and saidplate.
 39. The apparatus of claim 38 wherein said attachment membersinclude a first side for facing a vertebra and a second side facing saidplate, wherein said posts extend from said second sides of saidattachment members.
 40. The apparatus of claim 38 wherein said secondside of said first and second attachment members includes a matingportion such that said first post may be securely mated with said firstattachment member and said second post may be securely mated with saidsecond attachment member.
 41. The apparatus of claim 37 wherein saidaperture of said plate member is a circular aperture.
 42. The apparatusof claim 41 wherein said first and second attachment members have anupper side that is roughened.
 43. The apparatus of claim 42 wherein saidplate member has an underside, said underside being roughened in an areaproximate to said slot.
 44. The apparatus of claim 43 wherein saidunderside is roughened in an area proximate to said aperture.
 45. Theapparatus of claim 44 wherein said roughened area proximate to saidaperture of said plate member and said roughened area of said secondattachment member include one or more radial splines.
 46. The apparatusof claim 36 further comprising: a bolt having a lower portion includingthreads adapted to be inserted into a bone, and an upper portion havingthreads, said upper portion adapted to be inserted through at least theat least one hole of said attachment member and through said slot oraperture of said plate; and a nut adapted to be threaded onto said upperthreaded portion of said bolt for locking together said attachmentmember and said plate.
 47. The apparatus of claim 46 further comprising:a second bolt having a lower portion including threads adapted to beinserted into a bone, and an upper portion having threads, said upperportion adapted to be inserted through one of said at least one hole ofsaid second attachment member and through said slot or aperture of saidplate member; and a second nut adapted to be threaded onto said upperthreaded portion of said second bolt for locking together saidattachment member and said plate member.
 48. The apparatus of claim 36,wherein said screw includes a longitudinal cannula.
 49. The apparatus ofclaim 48, wherein said screw includes at least one opening communicatingwith and substantially perpendicular to said cannula.
 50. The apparatusof claim 49, wherein said screw includes multiple openings communicatingwith said cannula, said openings being substantially equiangularlyspaced from each other.
 51. The apparatus of claim 36, wherein saidattachment member includes a lower surface and at least one prongextending from said lower surface.
 52. The apparatus of claim 36,wherein said attachment member includes a base that is substantiallysymmetric in configuration about each of two orthogonal axes.
 53. Anapparatus comprising: a plate for providing stability to first andsecond vertebrae, said plate member having a first end and a second end,a slot at said first end, and an aperture at said second end; a firstattachment member connected to said plate, said attachment member havingat least one hole for receiving a portion of a bolt and adapted to beplaced in contact with only one of said first and second vertebrae; saidbolt having a lower portion including threads adapted to be insertedinto a bone, and an upper portion having threads, said upper portionadapted to be inserted through at least the at least one hole of saidfirst attachment member and through said slot or aperture of said plate;a nut adapted to be threaded onto said upper threaded portion of saidbolt for locking together said first attachment member and said plate. asecond attachment member connected to said plate, said second attachmentmember having at least one hole for receiving a portion of a boneanchoring member and adapted to be placed in contact with only the otherof said first and second vertebra.
 54. The apparatus of claim 53 furthercomprising: a second bolt having a lower portion including threadsadapted to be inserted into a bone, and an upper portion having threads,said upper portion adapted to be inserted through one of said at leastone hole of said second attachment member and through said slot oraperture of said plate member; and a second nut adapted to be threadedonto said upper threaded portion of said second bolt for lockingtogether said second attachment member and said plate member.
 55. Theapparatus of claim 54 wherein said slot of said plate has a longitudinalaxis, and said portion of said plate extends substantially transverselyto said axis.
 56. The apparatus of claim 55 wherein said plate has anunderside, said underside being roughened in an area proximate to saidaperture and said second attachment member has an area on an upper sidethat is roughened, such that contact between each of said roughenedareas aids in securely engaging said plate to said second attachmentmember.
 57. The apparatus of claim 53, wherein said plate has a lowerside and said attachment members each have a respective upper side, andsaid lower side of said plate is adjacent or contacting said upper sidesof said attachment members.
 58. A bone repositioning apparatus,comprising a toothed bar; first and second elongated rods connected tosaid bar and extending from said bar, at least one of said rodscomprising an outer sleeve and an inner shaft that partially extendsfrom said outer sleeve, said outer sleeve having a distal end that isinternally threaded, and said inner shaft having an external printconfigured to be accommodated in an internal print of an implant; and apinion mechanism connecting one of said rods to said bar, said pinionmechanism having a handle and a toothed wheel engaged with said toothedbar, wherein turning said handle turns said toothed wheel and moves saidmechanism and said rod connected to said mechanism with respect to saidbar.
 59. The apparatus of claim 58, wherein said outer sleeve includesat least one flattened external portion.
 60. The apparatus of claim 58,wherein said inner shaft includes at least one flattened externalportion.
 61. The apparatus of claim 58, wherein said pinion mechanismincludes a clamp having a screw for closing said clamp, and said firstrod is clamped in said clamp.
 62. The apparatus of claim 58, whereinsaid pinion mechanism includes a spring-loaded pawl that engages saidtoothed bar to prevent relative movement of said rods in one direction.